U.S. Pat. No. 5,716,625 describes the ability of topically-applied strontium, in divalent ionic form, to rapidly suppress acute sensory irritation (e.g., stinging, burning pain and/or itching) and accompanying inflammation due to chemical irritants, electromagnetic radiation, “environmental irritants” and diseases (strontium's “anti-irritant activity”).
While not being bound or otherwise limited by any particular biochemical mechanism, it was theorized that strontium's anti-irritant activity was due to the ability of strontium to selectively suppress activation of Type C Nociceptors (TCN), the only sensory nerves that produce and transmit stinging, burning pain and itching sensations and the neurogenic inflammatory response that can accompany TCN activation.
When compared to the existing topical drugs able to suppress such sensory irritation like lidocaine or Novocain™, the local anesthetic typically used by dentists during dental procedures, strontium has a unique property—it is highly selective for only the TCN and doesn't significantly affect the many other sensory nerves that provide normal tactile sensations and “cutaneous awareness.” Since lidocaine and other topical local anesthetics lack this specificity for TCN, they can cause numbness and loss of function.
While topically applied strontium can rapidly inhibit the activation of TCN sensory nerve subsets that transmit sensations of pain (e.g., burning and stinging) and pruritus (itching), recent investigations to understand strontium's anti-irritant mechanisms surprisingly reveal that strontium also has negative effects on several biochemical pathways that tend to negate the positive anti-irritant benefits of strontium for treatment of neuropathic conditions.
Therefore it is desirable to create new strontium-containing molecules, complexes and formulations that increase the “positive” therapeutic benefits of strontium and decrease the “negative” effects of strontium on acute pain, pruritis and neuropathic conditions